Hayley Milne & Andrew England a.england@salford.ac.uk Does using a lower kVp offer a greater potential for fracture detection in hip radiography? Hayley Milne & Andrew England a.england@salford.ac.uk

Introduction elderly population suspected hip fractures Prompt management essential (NICE, 2011) Non-displaced hip fractures Difficult to visualise Low bone density (Butler et al., 2009) kVp reduction  contrast

Aim To investigate whether a reduction in the tube potential (kVp) will increase the visibility of the bony trabecular pattern on antero-posterior (AP) hip images.

Materials & Methods Acroma X-ray Unit Pelvis Phantom Standard AP hip projection 100 cm SID Central AEC chamber Grid Agfa CR receptor Exposures (kVp) 50 – 100 Interval = 5 kVp Effective Dose calculated Images 3 per kVp setting Pseudoanonymised

Image Quality Assessment BACKGROUND Physical Signal-to-Noise Ratio (SNR) Contrast-to-Noise Ratio (CNR) Perceptual (Visual) 5 observers 2AFC Image Quality Scale Can the Principle Tensile Trabeculae (PTT) be visualised Can the Greater Trochanter Trabeculae (GTT) be visualised Can the Secondary Compressive Group (SCT) be visualised Overall image quality

} 2AFC Technique REFERENCE EXPERIMENTAL 80 kVp 50 to 75 kVp REFERENCE IMAGE EXPERIMENTAL IMAGE } Better than reference (4) Equal to reference (3) Worse than reference (2) EACH SCALE ITEM (n = 4)

Results – Radiation Dose 47%

Results – Signal to Noise Ratio

Results – Contrast to Noise Ratio

Results – Perceptual (Visual) 5 observers Final year students Reference image

Summary Lowering tube potential (kVp) Further work Potential impact Noticeable trends in the physical measures of trabecular pattern on AP hip radiographs Low kVp = Higher CNR No improvement in perceptual measures (high variability) Further work Clinical based studies needed Include cases of osteoporosis / osteopenia / subtle fractures Careful selection of IQ criteria + training Potential impact Low kVp acquisition parameters may provided an option for re-evaluating patients with suspected subtle hip fractures if other imaging modalities are not available. May offer more speedier diagnosis than further imaging (MRI, CT or NM)

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